JP4160999B2 - Water heater - Google Patents

Description

  The present invention relates to a hot water supply device that uses a hot water storage tank and a heating device in combination. In particular, when all of the hot water stored in the hot water tank is used up and the hot water is exhausted, and the temperature of the hot water supplied from the hot water tank to the heating device drops rapidly, the temperature of the hot water supplied to the hot water usage location changes greatly. It is related with the hot-water supply apparatus which can suppress doing.

An apparatus has been developed in which hot water heated by solar heat or generated heat is stored in a hot water storage tank, and hot water is supplied to a hot water use location. In case the hot water stored in the hot water tank has been used up and the hot water has run out, there is a device that supplies the hot water stored in the hot water tank to the hot water use location after passing through the heating device. Has been developed. According to this hot water supply apparatus, after the hot water stored in the hot water tank is used up, the hot water supply can be continued by heating with the heating apparatus.
FIG. 11 shows an example of an apparatus for storing hot water heated by using the generated heat generated with power generation in a hot water storage tank and supplying hot water to a hot water use location after passing through the heating device. This hot water supply apparatus is disclosed in Patent Document 1. The apparatus of FIG. 11 constitutes a cogeneration system (electricity and heat combined supply system) that generates and supplies hot water.

JP 2001-065975 A

  The cogeneration system includes a power generation device 130 that generates electric power and generated heat and a hot water supply device 100. The hot water supply device 100 stores hot water heated by the power generated by the power generation device 130 during power generation, and the hot water from the hot water storage tank 104 is mixed with tap water so that the temperature of the mixed hot water is adjusted to an appropriate temperature. A mixing unit 106 to be lowered, a heating device 108 that heats water after passing through the mixing unit 106, and a hot water supply pipe 118 that supplies hot water that has passed through the heating device 108 to the hot water use location 120 are provided.

A water supply pipe 110 that supplies tap water to the lower part of the hot water tank 104 is connected to the lower part of the hot water tank 104. A power generation heat recovery pipe 112 is provided that takes out cold water from the lower part of the hot water tank 104, heats the cold water by exchanging heat with the power generator 130, and returns the heated hot water to the upper part of the hot water tank 104. A hot water discharge pipe 114 is connected to the hot water stored in the hot water storage tank 104 to discharge the hot water stored in the mixing unit 106. The hot water supply pipe 114 communicates the upper part of the hot water storage tank 104 with the mixing unit 106. A water supply pipe 110 is connected to the mixing unit 106, and hot water discharged from the hot water storage tank 104 and tap water supplied from the water supply pipe 110 are mixed at an arbitrary ratio and lowered to an appropriate temperature. The hot water adjusted in temperature by the mixing unit 106 passes through a heating device 108 incorporating a burner and is supplied to a hot water supply pipe 118.
A hot water thermistor 124 that measures the temperature of the hot water before mixing by the mixing unit 106 and a cold water thermistor 126 that measures the temperature of the tap water before mixing by the mixing unit 106 are provided.

When the power generation device 130 performs a power generation operation, the circulation pump 122 is operated. Cold water is taken out from the lower part of the hot water tank 104, heat is exchanged with the power generation device 130 to heat the cold water, and the heated hot water is returned to the upper part of the hot water tank 104.
The hot water that has returned to the upper part of the hot water tank 104 has a lower specific gravity than the cold water stored in the lower part of the hot water tank 104, and therefore accumulates in the upper part of the hot water tank 104. The cold water before heating in the hot water storage tank 104 stays at the lower part of the hot water storage tank 104 because the specific gravity is larger than that of the hot water. By maintaining a state where almost no convection occurs between the hot water at the upper part of the hot water tank and the cold water at the lower part, the hot water is stored in the upper part of the hot water tank 104 and the cold water is stored in the lower part. A temperature stratification that does not mix is formed.

  When hot water is used at the hot water use location 120 and hot water is discharged from the hot water storage tank 104, tap water corresponding to the amount of hot water discharged is supplied from the water supply pipe 110 to the lower part of the hot water storage tank 104. The hot water in the hot water storage tank 104 is pushed up by tap water supplied from the water supply pipe 110 while maintaining temperature stratification. All the hot water in the hot water storage tank 104 can be used up in order to discharge hot water from the hot water discharge pipe 114 communicating with the uppermost part of the hot water storage tank 104.

The hot water supply apparatus 100 adjusts the hot water temperature supplied to the hot water supply pipe 118 to a temperature specified by the hot water user. Hereinafter, the temperature designated by the hot water user is referred to as a set temperature T3.
When the tapping temperature T1 before mixing by the mixing unit 106 is higher than the set temperature T3, the mixing unit 106 mixes with tap water and adjusts the temperature to the set temperature T3. The hot water adjusted to the set temperature T3 by the mixing unit 106 passes through the heating device 108 and is supplied to the hot water supply pipe 118. In this case, the heating device 108 does not perform the heating operation, and the hot water adjusted to the set temperature T3 passes through the heating device 108. Since the temperature stratification is maintained in the hot water storage tank 104, hot hot water is discharged to the mixing unit 106 until the hot water stored in the hot water storage tank 104 is used up. In many cases, the temperature can be adjusted to the set temperature T3 without using the heating device. For this reason, the amount of fuel used in the heating device 108 can be reduced, and energy can be saved. In order to adjust the temperature to the set temperature T3 by the mixing unit 106, the hot water temperature T1 and the tap water temperature T2 before mixing by the mixing unit 106 are measured, and the mixing ratio of the hot water and tap water is obtained from the measurement result.

  When the hot water temperature T1 is lower than the set temperature T3, the hot water discharged from the hot water storage tank 104 is mixed with tap water in the mixing unit 106 in consideration of the heating amount of the heating device 108, and passes through the mixing unit 106. Then, the hot water heated to the set temperature T3 is supplied to the hot water use location 120.

While the hot water remains in the hot water storage tank 104, the hot water is pushed up in a state where the temperature stratification is maintained, so that the hot water having a relatively stable temperature is discharged to the mixing unit 106. In other words, since hot hot water is discharged from the hot water storage tank 104 until the last moment when the hot water is used up, the temperature of the water discharged into the mixing unit 106 is drastically lowered when the hot water is used up.
The mixing unit 106 attempts to maintain the water temperature after mixing at the set temperature T3 by lowering the tap water mixing ratio following the decrease in the tapping temperature T1. When the mixed water temperature cannot be maintained at the set temperature T3, a combustion start command is output to the heating device 108.
If the mixing unit 106 has high mixing ratio followability to temperature changes and the heating amount adjustment speed of the heating device 108 is fast, the temperature of the hot water supplied to the hot water supply pipe 118 does not change even if the hot water in the hot water storage tank 104 is used up. It should be. However, in reality, this is not the case, and the temperature of the hot water supplied to the hot water supply pipe 118 is once lowered when the water is exhausted.

In FIG. 12, with respect to the elapsed time (horizontal axis), the hot water temperature T1 at the inlet of the mixing unit 106, the hot water supply temperature T4 for supplying hot water to the hot water use location 120, and the heating amount (gas supply per unit time). (Shown in quantity).
Hot water supply apparatus 100 monitors hot water temperature T <b> 1 entering mixing unit 106 by hot water thermistor 124. Period 1 indicates a period in which a sufficient amount of hot water is stored in the hot water storage tank 104 and the hot water temperature T1 is stable at a temperature higher than the hot water supply set temperature T3. In period 1, the heating device 108 does not burn, and hot water discharged from the hot water storage tank 104 is mixed with tap water by the mixing unit 106 and adjusted to the set temperature T 3, and then the pipe 116, the heating device 108, and the hot water supply Hot water is supplied to the hot water use point 120 through the pipe 118.
When the hot water in the hot water storage tank 104 is low, the hot water temperature T1 entering the mixing unit 106 starts to drop rapidly. The hot water supply device 100 starts the control in the period 2 when the tapping temperature T1 falls below a preset control start temperature (mixing rate change temperature). The hot water supply apparatus 100 reduces the mixing ratio of tap water over time by restricting the tap water valve of the mixing unit 106. Normally, the hot water temperature T1 entering the mixing unit 106 decreases rapidly, so even if the mixing ratio of the tap water is decreased by the mixing unit 106, the hot water temperature after mixing cannot be maintained at the hot water supply set temperature T3. The hot water supply device 100 throttles the tap water valve until the ratio of tap water to be mixed becomes zero. It takes time until the mixing ratio of the tap water actually decreases after the hot water supply device 100 starts the throttle operation of the tap water valve of the mixing unit 106. As a result, the operation of reducing the mixing ratio of tap water cannot follow the rapid decrease in the hot water temperature T1 when the hot water in the hot water storage tank 104 is used up, and the hot water supply temperature T4 gradually decreases.

When the tapping temperature T1 falls below the ignition determination temperature, the hot water supply apparatus 100 determines that the set temperature T3 cannot be maintained only by adjusting the mixing ratio of the mixing unit 106, and starts control for the period 3. In period 3, an ignition command is issued to the heating device 108, and heating of the water is started by the heating device 108.
Even if an ignition command is issued to the heating device 108, the heating amount of the heating device 108 does not increase suddenly. A certain amount of time is required until the heating device 108 actually starts the ignition process, and since there are many unstable combustion conditions immediately after the ignition, the gas supply amount cannot be increased rapidly. . Since a delay occurs until the heating amount increases, the hot water supply temperature T4 continues to decrease for a while even during the period 3. The hot water supply temperature T4 can be returned to the set temperature T3 only after the combustion amount of the heating device 108 increases.

  When the heating device 108 can adjust the heating amount to a sufficient level, the hot water supply device 100 starts the control in the period 4. In period 4, the amount of gas supplied to the heating device 108 is controlled to heat the hot water supplied to the hot water use location 120 to the set temperature T3. When all the hot water in the hot water storage tank 104 is exhausted, the temperature T1 of the water discharged from the hot water storage tank 104 is lowered to the temperature T2 of tap water. Even in this case, the tap water can be heated to the set temperature T3 by the heating device 108 to supply hot water.

  In the conventional hot water supply apparatus 100, when the hot water stored in the hot water storage tank 104 is used up and the temperature of the hot water discharged from the hot water storage tank 104 decreases rapidly, the temperature T4 of the hot water supplied to the hot water use location 120 temporarily decreases. After a while, the temperature finally returns to the set temperature T3. If the hot water supply temperature at the hot water use location 120 is temporarily changed, the hot water user is uncomfortable, and improvement is required.

  The present invention has been made in view of the above-mentioned problems, and when all the hot water stored in the hot water tank is used and the hot water runs out, the temperature of the hot water discharged from the hot water tank rapidly decreases. Moreover, the hot water supply apparatus which can suppress that the temperature of the hot water supplied to a hot water use location changes greatly is provided. Moreover, the cogeneration system which can suppress the change of hot water supply temperature is provided.

  The present invention relates to a hot water storage tank, a mixing unit that mixes hot water and tap water from the hot water storage tank, a heating device that heats water after passing through the mixing unit, and a hot water supply that supplies hot water that has passed through the heating device to a hot water use location. The present invention relates to a hot water supply apparatus having a pipe. The heating device heats the passing water as needed. In addition, in this specification, water is not limited to cold water, and hot water or hot water may be referred to as water.

In one embodiment of the present invention, a water supply pipe for supplying tap water to the hot water pipe connecting the hot water tank and the mixing unit is connected. Hot water from the hot water storage tank, after being mixed with tap water from the water supply pipe and is mixed with tap water further mixing unit.
When tap water is supplied to the hot water supply pipe connecting the hot water storage tank and the mixing unit, the hot water discharged from the hot water storage tank mixes with the hot water, and the hot water temperature is lowered before entering the mixing unit. In this case, the changing speed of the hot water temperature input to the mixing unit is slow.
Before the hot water tank runs out, the hot water entering the mixing unit is mixed with tap water from the water supply pipe and the temperature is lowered. Since the mixing unit can be adjusted to a set temperature by mixing with a small amount of tap water, the tap water valve in the mixing unit is throttled to mix a small amount of water.
When the hot water supplied to the mixing unit gradually falls due to the hot water tank running out of water (compared to the case where the hot water supplied to the mixing unit is not mixed with the tap water from the water supply piping, the water supply from the water supply piping When the mixture is mixed with water and then fed into the mixing unit, the temperature change is slow.) In the mixing unit, the tap water tap already throttled is further throttled. When the temperature of the hot water supplied to the mixing unit changes rapidly, it is difficult for the mixing unit to change the mixing ratio of tap water following the temperature change. However, the operation of further reducing the tap water valve that has already been throttled is fast in response because the valve opening / closing amount is small. In addition, since the temperature drop of the hot water entering the mixing unit is gradual, even when the tap water valve is throttled at a normal operation speed, the mixing ratio of the tap water can be lowered following the decrease in the hot water temperature. . Even if the temperature of the hot water discharged from the hot water storage tank drops rapidly when the hot water runs out, the temperature change of the hot water sent from the mixing unit can be suppressed.

  When the temperature of the hot water discharged from the hot water storage tank further decreases, the heating device starts heating. Preparation time is required until the hot water discharged from the hot water tank starts to be heated by the heating device. However, since the temperature of the hot water gradually decreases, the heating device starts to heat to the hot water supply set temperature. The fall of the hot water supply temperature can be suppressed.

  By connecting a water supply pipe that supplies tap water to the hot water pipe that connects the hot water storage tank and the mixing unit, the temperature change of the hot water entering the mixing unit can be moderated, and the hot water and water supply follow the gentle temperature change. The mixing ratio of water can be changed, and the heating amount of the heating device can be changed. The temperature change of the hot water supplied to a hot water utilization location can be suppressed by the above.

In another specific example of the present invention, the hot water piping connecting the hot water storage tank and the mixing unit is communicated with the hot water storage tank at two or more places having different heights.
If the hot water supply pipe communicates with the hot water storage tank at two or more places having different heights, the hot water is taken out from different positions in the hot water storage tank and supplied to the mixing unit.
Temperature stratification is formed in the water stored in the hot water tank, and the hot water remaining in the hot water tank is pushed upward as the hot water in the hot water tank is used. When the hot water is pushed up above the lowest communication position among the plurality of communication locations between the hot water supply pipe and the hot water storage tank, the temperature of the water discharged from the communication location rapidly decreases. Cold water discharged from a low communication point is mixed with hot water discharged from a hot water discharge pipe communicating with the upper part, and enters the mixing unit. The temperature of the hot water after mixing begins to fall slowly from an early stage reflecting the temperature change of the water discharged from the lowest communication point.

If the hot water supply pipe is connected to the hot water storage tank at two or more places having different heights, the temperature of the hot water supplied to the mixing unit begins to decrease earlier than when the hot water supply pipe is connected at one place. Thereby, it is possible to quickly know that the hot water tank has run out.
In addition, since water that rapidly decreases in temperature and hot water that is stable at high temperature are mixed, the temperature change at the inlet of the mixing unit to which the hot water after mixing is supplied is gentle.
When the temperature of the input hot water starts to drop, the mixing unit performs an operation of gradually reducing the tap water valve. Since the temperature change of the hot water can be known at an early timing and the temperature drop of the warm water is gradual, the tap water follows the temperature drop of the hot water even when the tap water valve is throttled at the normal operation speed. The mixing ratio can be lowered. It is possible to suppress the temperature change of the hot water delivered from the mixing unit.
The heating device starts heating the hot water when the temperature of the hot water discharged from the hot water storage tank further decreases. Since the temperature drop of the warm water is moderate, it is possible to suppress the hot water supply temperature from being lowered before the heating device starts heating to the hot water supply set temperature.

In yet another specific example of the present invention, the hot water pipe connecting the hot water storage tank and the mixing unit has a hot water storage tank at a lower position via a heat exchanger for exchanging heat with hot water stored in the upper part of the hot water storage tank. It is characterized by communicating with.
If the hot water piping connecting the hot water storage tank and the mixing unit communicates with the hot water storage tank at a lower position via a heat exchanger that exchanges heat with the hot water stored in the hot water storage tank, the hot water in the hot water storage tank When the water is pushed up and cold water begins to enter the hot water supply pipe, the cold water is heated by the hot water in the upper part of the hot water tank and then discharged. If the cold water is heated and then supplied to the mixing unit, the temperature of the hot water entering the mixing unit begins to decrease earlier than before, and the temperature change is gentler. Even when it is squeezed at a normal operation speed, the mixing ratio of tap water can be lowered following the decrease in hot water temperature. Thereby, the change of the warm water temperature sent out from a mixing unit is suppressed.
The heating device starts heating the hot water when the tapping temperature further decreases. Since the temperature drop of the hot water delivered from the mixing unit is gentle, it is possible to suppress the hot water supply temperature from dropping before the heating device starts heating to the hot water supply set temperature.
The hot water remaining above the communication point of the hot water tank is not supplied to the mixing unit, but is cooled by supplying heat to the cold water passing through the heat exchanger. Thus, the heat stored in the hot water tank can be used up. The amount of heat stored in the hot water is not wasted.

  Cogeneration systems often generate electricity when hot water is supplied. In this case, it is preferable to connect the hot water supply pipe connecting the hot water storage tank and the mixing unit to the upper part of the hot water storage tank, and connect the power generation heat recovery pipe to the hot water storage tank at a height below the communication height by a predetermined distance.

The hot water recovered from the generated heat is returned to the hot water storage tank at a position lower than the hot water position by communicating the generated heat recovery pipe at a height lower than the hot water pipe by a predetermined distance. If the temperature of the water stored above the connection point of the power generation heat recovery pipe is lower than the temperature of the hot water entering the hot water tank from the power generation heat recovery pipe, convection will occur and low temperature water and high temperature water will be mixed. Fit. The temperature distribution of the hot water above the communication point of the power generation heat recovery pipe is uniform.
When hot water more than the amount supplied from the power generation heat recovery pipe is used during power generation and the remaining amount of hot water in the hot water storage tank is reduced, the cold water rises around the communication point of the power generation heat recovery pipe. Also at this time, the high temperature water and the low temperature water are mixed by convection, so that the hot water above the communication point of the power generation heat recovery pipe is kept at a uniform temperature.
Even when hot water exceeding the amount supplied from the heat generation heat recovery piping is used during power generation, the hot water above the communication heat recovery piping connection is kept at a uniform temperature by convection. The temperature of hot water discharged from the hot water gradually decreases. It is possible to effectively suppress fluctuations in hot water supply temperature by controlling the mixing ratio of the hot water and tap water in the mixing unit and the heating amount following the gentle temperature change of the hot water discharged from the hot water tank. it can.

In the hot water supply apparatus of the present invention, hot water is stored in a hot water tank, and the hot water adjusted to the set temperature is supplied to the hot water use location using a mixing unit and a heating device.
In one specific example, the temperature change of the hot water entering the mixing unit when the hot water tank is out of hot water by mixing tap water with a certain ratio to the hot water discharged from the hot water tank and supplying it to the mixing unit. The temperature adjustment by the mixing unit and the heating device closely follows the temperature change of the hot water, and the hot water supply temperature can be kept near the set temperature.
In another specific example, the hot water temperature entering the mixing unit is changed before the hot water tank runs out by discharging hot water from two or more places having different heights. You can know when the hot water has run out earlier. Furthermore, in such a hot water supply device, the temperature change of the hot water discharged from the hot water tank when the hot water runs out is gradual, and the mixing unit and the heating device can be adjusted to closely follow the change in the hot water temperature. The hot water supply temperature can be kept near the set temperature.
The same effect can be obtained even if the hot water piping communicates with the hot water storage tank at a position below the hot water storage tank via a heat exchanger that exchanges heat with the hot water above the hot water storage tank.
Furthermore, convection can be generated at the upper part of the hot water tank by lowering the communication height of the power generation heat recovery pipe and hot water tank by a predetermined distance from the communication height of the hot water piping and hot water tank. The distribution can be made uniform. Even with this cogeneration system, the temperature change of the hot water supplied from the hot water tank becomes gentle when the hot water tank runs out, and the hot water temperature is kept near the set temperature by adjusting the temperature with the mixing unit and heating device. Can do.

The main features of the embodiments described below are listed below.
(Mode 1) The hot water supply apparatus has control means for controlling the opening / closing amount of a valve for supplying tap water to the mixing unit and the combustion amount of the burner.
(Mode 2) Hot water inside the hot water tank forms a temperature stratification.
(Mode 3) Tap water is supplied from the feed water pipe connected to the tap water pipe at a constant ratio to the hot water flowing through the tap water pipe. The hot water discharged from the hot water tank and the tap water supplied from the water supply pipe are mixed and enter the mixing unit.
(Form 4) The water intake is provided in two or more places from which the height of a hot water storage tank differs. The hot water piping is branched on the hot water tank side and connected to each water intake.
(Mode 5) The hot water supply pipe extends downward in the hot water storage tank via a heat exchanger that exchanges heat with hot water stored in the upper part of the hot water storage tank. The tip of the pipe is a water intake, and hot water in the hot water tank is taken out.
(Mode 6) The hot water supply pipe enters the hot water storage tank from the upper part of the hot water storage tank, and extends downward in the hot water storage tank. Water intakes are provided at a plurality of positions where the heights of the pipes extending downward are different.
(Mode 7) A heat exchanger is provided in the upper part of the hot water tank, and the power generation heat recovery pipe for heating the water stored in the lower part of the hot water tank with the generated heat and returning it to the upper part of the hot water tank is more than the heat exchanger. It communicates with the hot water tank at the bottom.

Hereinafter, an embodiment in which a hot water supply apparatus of the present invention is applied to a cogeneration system will be described in detail with reference to the accompanying drawings.
First Embodiment FIG. 1 shows a configuration of a cogeneration system according to a first embodiment of the present invention. The cogeneration system of the present embodiment includes a power generation device 32 that generates electric power and generated heat, and a hot water supply device 2. The hot water supply device 2 stores hot water heated by the generated heat generated by the power generation device 32 during power generation, and mixes hot water from the hot water storage tank 4 with tap water so that the temperature of the mixed hot water is adjusted to an appropriate temperature. A mixing unit 6 to be lowered, a heating device 8 that heats water after passing through the mixing unit 6, and a hot water supply pipe 18 that supplies hot water that has passed through the heating device 8 to the hot water use location 20 are provided.

A water supply pipe 10 for supplying tap water to the lower part of the hot water tank 4 is connected to the lower part of the hot water tank 4. A power generation heat recovery pipe 12 is provided which takes out cold water from the lower part of the hot water tank 4, heats the cold water by exchanging heat with the power generator 32, and returns the heated hot water to the upper part of the hot water tank 4. A hot water supply pipe 14 for discharging hot water stored in the hot water storage tank 4 to the mixing unit 6 is connected. The hot water supply pipe 14 communicates the upper part of the hot water storage tank 4 with the mixing unit 6. A water supply pipe 10 is connected to the mixing unit 6, and hot water discharged from the hot water tank 4 and tap water supplied from the water supply pipe 10 are mixed at an arbitrary ratio and lowered to an appropriate temperature. The mixing unit 6 has a valve that can control the amount of hot water supplied from the hot water supply pipe 14 and a valve that can control the amount of tap water supplied from the water supply pipe 10. Can be mixed at a ratio of The mixing ratio of hot water and tap water is controlled by the control means 30. The hot water adjusted in temperature by the mixing unit 6 passes through a heating device 8 incorporating a burner and is supplied to a hot water supply pipe 18. The heating device 8 can heat the passing water with combustion heat. The heating device 8 has an upper limit value and a lower limit value of the combustible amount, and the combustion amount can be adjusted between them. The amount of combustion in the heating device 8 is controlled by the control means 30.
A hot water thermistor 24 that measures the temperature of the hot water before mixing by the mixing unit 6 and a cold water thermistor 26 that measures the temperature of the tap water before mixing by the mixing unit 6 are provided.
Further, a water supply pipe 40 branches from the water supply pipe 10 and is connected to the hot water supply pipe 14. From the branch water supply pipe 40, tap water is always supplied at a constant ratio with respect to the hot water discharged from the hot water tank 4. The mixing ratio of tap water is adjusted in advance to a constant value based on the temperature of hot water normally stored in the hot water tank 4, the temperature of tap water, and the hot water supply set temperature that is normally set. That is, the mixing ratio of the tap water is determined so that the temperature of the hot water mixed with the tap water and entering the mixing unit 6 becomes higher than the normal hot water supply set temperature. Hot water discharged from the hot water tank 4 and tap water supplied from the branch pipe 40 are mixed and enter the mixing unit 6.

  The generator 32 includes a reformer 34 and a polymer electrolyte fuel cell 36. The reformer 34 reacts the raw material gas and water to generate hydrogen gas used by the fuel cell. Since the hydrogen gas is generated at a high temperature, the high-temperature exhaust gas is discharged from the reformer 34. The fuel battery cell 36 generates power using hydrogen gas and oxygen supplied from the reformer 34 as raw materials. The fuel cell 36 generates heat during power generation. Cooling water circulates and cools in the fuel cell 36 so that the fuel cell 36 during power generation does not overheat. The cold water flowing through the power generation heat recovery pipe 12 is heated by the heat generated by the fuel cell 36 and further heated by the high-temperature exhaust gas from the reformer 34.

  The control device 30 controls the mixing ratio of the hot water and tap water in the mixing unit 6, the timing of ignition of the heating device 8, and the amount of combustion so that the temperature of the hot water supplied to the hot water use location 20 becomes a preset temperature. To control. For this purpose, the control means 30 reads the temperature T1 measured by the hot water thermistor 24 and the temperature T2 measured by the cold water thermistor 26 and performs necessary calculations. Then, the mixing unit 6 and the heating device 8 are controlled in accordance with changes in the temperatures T1 and T2.

While the power generation device 32 performs the power generation operation, the circulation pump 22 is operated. Cold water is taken out from the lower part of the hot water tank 4, heat is exchanged with the power generation device 32 to heat the cold water, and the heated hot water is returned to the upper part of the hot water tank 4.
The hot water that has returned to the upper part of the hot water tank 4 has a lower specific gravity than the cold water stored in the lower part of the hot water tank 4, and therefore accumulates in the upper part of the hot water tank 4. The cold water before heating in the hot water tank 4 stays at the lower part of the hot water tank 4 because the specific gravity is larger than that of the hot water. By maintaining a state where almost no convection occurs between the hot water at the upper part of the hot water tank and the cold water at the lower part, the hot water is stored in the upper part of the hot water tank 4 and the cold water is stored in the lower part. A temperature stratification that does not mix is formed.

  When hot water is used at the hot water supply use location 20 and hot water is discharged from the hot water storage tank 4, an amount of tap water corresponding to the amount of hot water discharged is supplied from the water supply pipe 10 to the lower part of the hot water storage tank 4. The hot water in the hot water storage tank 4 is pushed up by the tap water supplied from the water supply pipe 10 while maintaining the temperature stratification. All the hot water in the hot water storage tank 4 can be used up in order to discharge hot water from the hot water supply pipe 14 communicating with the uppermost part of the hot water storage tank 4.

The hot water supply device 2 adjusts the hot water temperature supplied to the hot water supply pipe 18 to a temperature specified by the hot water user. The temperature specified by the hot water user is referred to as a set temperature T3.
When the tapping temperature T1 before mixing by the mixing unit 6 is higher than the set temperature T3, the mixing unit 6 mixes with tap water and adjusts the temperature to the set temperature T3. The hot water adjusted to the set temperature T3 by the mixing unit 6 passes through the heating device 8 and is supplied to the hot water supply pipe 18. In this case, the heating device 8 does not execute the heating operation, and the hot water adjusted to the set temperature T3 passes through the heating device 8. Since the temperature stratification is maintained in the hot water tank 4, hot hot water is discharged to the mixing unit 6 until the hot water stored in the hot water tank 4 is used up. In many cases, the temperature can be adjusted to the set temperature T3 without using the heating device 8. For this reason, the amount of fuel used in the heating device 8 can be reduced, and energy can be saved. In order to adjust the temperature to the set temperature T3 by the mixing unit 6, the hot water temperature T1 and the tap water temperature T2 before mixing by the mixing unit 6 are measured, and the mixing ratio of the hot water and tap water is obtained from the measurement result.

  When the tapping temperature T1 is lower than the set temperature T3, the hot water fed from the tapping piping 14 to the mixing unit 6 is mixed with the tap water in the mixing unit 6 in consideration of the heating amount of the heating device 8 and mixed. 6 is heated to the set temperature T3 by the heating device 8, and the hot water heated to the set temperature T3 is supplied to the hot water use location 20.

The hot water supply device 2 controls the mixing unit 6 and the heating device 8 by the control means 30, and supplies the hot water adjusted to the set temperature T3 to the hot water use location 20. Hereinafter, with reference to FIG. 2, with respect to the elapsed time (horizontal axis), the hot water temperature T1 at the inlet of the mixing unit 6, the hot water supply temperature T4 for supplying hot water to the hot water use location 20, and the heating amount (unit) It shows how the gas supply amount per hour) changes.
Here, the period during which hot water is supplied will be described by dividing it into four periods from period 1 to period 4.

In the period 1 of FIG. 2 in which hot water is supplied with hot water stored in the hot water tank 4, the hot water temperature T1 at the inlet of the mixing unit 6 is higher than the hot water supply set temperature T3. Since the tap water from the branch pipe 40 is mixed, the hot water temperature T1 at the inlet of the mixing unit 6 is lower than the outlet temperature of the hot water tank 4 (shown by a dotted line). Still, it is higher than the hot water supply set temperature T3.
The control means 30 calculates the mixing ratio of tap water that can adjust the mixed hot water to the set temperature T3 from the measurement results of the hot water temperature T1 and the tap water temperature T2, and based on the calculation result, for the tap water of the mixing unit 6 Determine the amount of valve opening. The opening amount of the valve at this time is smaller than when the tap water is not supplied from the branch pipe 40.
The hot water at the temperature T1 from the hot water supply pipe 14 is mixed with the tap water at the temperature T2 by the mixing unit 6 to become the set temperature T3, and is supplied to the hot water usage point 20 through the hot water supply pipe 18.

  When the hot water is discharged from the hot water storage tank 4 to the hot water supply pipe 14, tap water corresponding to the amount of hot water discharged is supplied from the water supply pipe 10 to the lower part of the hot water storage tank 4, and the remaining hot water is supplied to the upper part of the hot water storage tank 4. Push up. Further, when hot water is used and hot water runs out, tap water entered from the water supply pipe 10 passes through the hot water storage tank 4 and is supplied to the hot water discharge pipe 14 as it is, so that the hot water temperature in the hot water storage tank 4 rapidly decreases. However, in this embodiment, since the hot water whose temperature has been lowered by the tap water from the water supply pipe 40 is sent to the mixing unit 6, the temperature of the hot water sent to the mixing unit 6 is slower than the temperature of the hot water in the hot water storage tank 4. To drop. The temperature T1 of the hot water fed into the mixing unit 6 gradually decreases as compared with the rate of decrease in the hot water temperature of the hot water tank 4 indicated by the broken line in FIG.

  When the control means 30 knows the decrease in the hot water temperature T1 fed into the mixing unit 6, it starts the control for the period 2. In the control of period 2, the mixing ratio of the hot water and tap water in the mixing unit 6 is recalculated based on the temperature T1 and the temperature T2, and the opening amount of the tap water valve of the mixing unit 6 is changed based on the recalculation result. To do. When the hot water temperature T1 fed into the mixing unit 6 decreases due to running out of hot water, the control means 30 follows the decrease of the temperature T1 and further throttles the tap water valve in stages. In the period 1, the tap water valve of the mixing unit 6 is already throttled. Even if the tap water valve is squeezed at a normal operating speed because the temperature of the hot water T1 fed into the mixing unit 6 is gradual and the tap water valve is not squeezed, the throttle operation of the tap water valve is limited. Can be performed following the decrease in temperature T1. Since the mixing ratio of the tap water can be lowered following the decrease in the temperature of the hot water sent to the mixing unit 6, the temperature of the hot water sent from the mixing unit 6 can be kept near the hot water supply temperature T3.

When the temperature T1 falls below the ignition determination temperature, the control means 30 determines that it cannot be maintained at the set temperature T3 only by changing the mixing ratio of the mixing unit 6, and starts the control for the period 3. In period 3, an ignition command is issued from the control means 30 to the heating device 8, and heating by the heating device 8 is started.
The control means 30 performs the ignition determination based on the ignition determination temperature only when the temperature T1 continues to decrease and the throttle operation of the tap water valve of the mixing unit 6 is repeated. The ignition determination temperature is set higher than the hot water supply set temperature T3, and tap water is mixed by the mixing unit 6 when an ignition command is issued to the heating device 8. When the temperature T1 further decreases and becomes lower than the hot water supply set temperature T3, the control means 30 throttles the tap water valve of the mixing unit 6. The hot water from the hot water tank 4 is mixed with tap water by the mixing unit 6 in consideration of the heating amount of the heating device 8 and supplied to the heating device 8 through the pipe 16.

When receiving the ignition command, the heating device 8 ignites a small amount of fuel gas. After confirming the ignition, gradually increase the gas supply amount to increase the combustion amount.
The heating device 8 can start heating before the hot water supply temperature is significantly lower than the hot water supply set temperature because the temperature T1 gradually decreases. Although there is a case where the heat energy is insufficient before and after the start of heating and the hot water supply temperature is slightly lowered, the temperature of the hot water passing through the heating device 8 rises rapidly as the combustion amount increases. The decrease in hot water supply temperature is suppressed to a very small level, and the hot water supply temperature can be maintained substantially at the set temperature.

  When the heating device 8 finishes the ignition mode and can adjust the combustion amount, the control means 30 starts the control in the period 4. In the period 4, the heat energy necessary for heating the water supplied to the heating device 8 to the set temperature is calculated, and the gas supply amount of the heating device 8 is obtained. Based on the calculation result, the heating device 8 is combusted at an optimal air-fuel ratio, and the water to be supplied to the hot water use location 20 is heated. Even when all the hot water in the hot water tank 4 is exhausted and the temperature T1 of the water supplied from the hot water tank 4 is lowered to the temperature T2 of the tap water, the heating device 8 can heat the tap water to the set temperature T3. it can.

  The hot water supply apparatus 2 of the present embodiment connects a hot water supply pipe 40 to a hot water supply pipe 14 connecting the hot water storage tank 4 and the mixing unit 6, supplies a certain amount of tap water to the hot water discharged from the hot water storage tank 4, and sets hot water supply The temperature is lowered to a temperature close to the temperature and supplied to the mixing unit 6. For this reason, even when the hot water storage tank 4 is in a hot water condition and the hot water temperature is rapidly lowered, the temperature change of the hot water fed into the mixing unit 6 becomes gentle. Since the temperature change is gradual, the mixing unit 6 can follow the temperature change, and the change in the temperature of the hot water sent from the mixing unit 6 is suppressed. Therefore, the temperature change of the hot water sent to the heating device 8 becomes gentle, the heating device 8 can follow the temperature change, and the change in the temperature of the hot water sent from the heating device 8 is suppressed. A change in the temperature of hot water supplied to the hot water use location 20 is suppressed.

(2nd Example) As shown in FIG. 3, the hot water supply apparatus 42 integrated in the cogeneration system of this Example has the hot water piping which connects the hot water storage tank 4 and the mixing unit 6 in two places from which height differs. It communicates with the hot water tank 4. That is, the hot water supply pipe 14 extending from the uppermost part of the hot water storage tank 4 and the hot water supply pipe 44 connected to the side surface of the hot water storage tank 4 are joined together and connected to the mixing unit 6. An approximately equal amount of water is supplied from the hot water storage tank 4 to each of the hot water supply pipe 44 and the hot water supply pipe 14. A hot water thermistor 24 is provided downstream of the connecting portion between the hot water piping 14 and the hot water piping 44, and measures the inlet temperature T <b> 1 of the mixing unit 6.

The contents of the hot water supply operation of the hot water supply apparatus 42 will be described with reference to FIG. A temperature TH indicated by a broken line in FIG. 4 is a temperature of hot water discharged from the hot water supply pipe 14, and a temperature TL is a temperature of hot water discharged from the hot water storage tank 4 to the hot water supply pipe 44.
The hot water storage tank 4 and the mixing unit 6 communicate with each other via the hot water supply pipe 14 and the hot water supply pipe 44, so that approximately equal amounts of hot water are taken out from different positions and supplied to the mixing unit 6. Temperature stratification is formed in the water stored in the hot water tank 4, and as the hot water in the hot water tank 4 is used, tap water is supplied from the water supply pipe 10, and the remaining hot water is pushed up.
When the hot water in the hot water storage tank 4 is pushed up above the location where the hot water outlet pipe 44 is connected, the temperature TL of the hot water discharged from the hot water outlet pipe 44 rapidly decreases. The remaining hot water is supplied to the hot water supply pipe 14, and the temperature TH is high and stable. Hot water taken from different positions of the hot water tank 4 is mixed at the junction of the hot water supply pipe 14 and the pipe 44 and enters the mixing unit 6. The inlet temperature T1 of the mixing unit 6 is substantially equal to the average value of the temperature TL and the temperature TH, and starts to fall early reflecting the temperature change of the TL.

The temperature T1 of the water supplied to the mixing unit 6 is earlier than that of the conventional hot water supply apparatus in which the hot water supply pipe 14 connecting the hot water storage tank 4 and the mixing unit 6 communicates only at the uppermost part of the hot water storage tank 4. appear. Further, the temperature T1 of the water supplied to the mixing unit 6 is gradually lowered because the temperature TH is stable at a high temperature.
When the temperature T1 starts to decrease, the control means 30 performs an operation of gradually reducing the tap water valve of the mixing unit 6. Since the change in the temperature T1 can be known at an early timing and the decrease in the temperature T1 is gradual, the tap water follows the decrease in the temperature T1 even when the tap water valve is throttled at a normal operation speed. The mixing ratio can be lowered.
When the hot water tank 4 runs out of hot water and the temperature TH starts to decrease, the temperature change of the temperature T1 increases. However, the tap water valve of the mixing unit 6 is throttled step by step while the temperature TH is stable, and a long response time is not required when the valve is continuously throttled. The response delay of the valve throttling operation with respect to the rapid temperature change of the temperature T1 does not increase, and the hot water temperature supplied from the mixing unit 6 can be kept near the hot water supply set temperature.

  When the temperature T1 falls below the ignition determination temperature, the control unit 30 starts the control in the period 3 and issues an ignition command to the heating device 8. The control means 30 performs the ignition determination using the ignition determination temperature only when the temperature T1 continues to decrease and the throttle operation of the tap water valve of the mixing unit 6 is repeated. By adjusting the set temperature of the ignition determination temperature, preparation for heating of the heating device 8 can be completed and heating of the hot water can be started before the hot water supply temperature greatly falls below the hot water supply set temperature.

  In the hot water supply apparatus 42 of the present embodiment, the hot water supply pipe connecting the hot water storage tank 4 and the mixing unit 6 communicates with the hot water storage tank 4 at two places having different heights. From the temperature change of the hot water supplied from the hot water supply pipe 44 that communicates at a low location, the control means 30 knows that the hot water storage tank 4 has run out at an earlier timing, and can control the mixing unit 6 at an earlier timing. In addition, since the temperature change of the initial hot water that has run out of water gradually occurs by mixing hot water supplied from different heights, the control means 30 throttles the tap water valve of the mixing unit 6. The control and the control of the combustion amount of the heating device 8 follow the temperature change of the hot water well. The hot water supply device 42 can keep the hot water supply temperature substantially constant when the hot water storage tank 4 runs out of hot water.

(Third embodiment) As shown in FIG. 5, in the hot water supply device 52 of this embodiment, a hot water supply pipe 14 that connects the hot water storage tank 4 and the mixing unit 6 enters the hot water storage tank 4 from the top of the hot water storage tank 4. The hot water tank 4 communicates with the hot water tank 4 at a lower position via a heat exchanger 54 that exchanges heat with the hot water stored in the upper part of the hot water tank 4. The communicating place is a hot water intake 56 of the hot water tank 4.

A state when hot water is supplied from the hot water supply device 52 will be described with reference to FIG. The control means 30 controls the mixing unit 6 and the heating device 8 with the same contents as the second embodiment with respect to the change of the temperature T1.
The hot water supply pipe 14 discharges hot water from the hot water storage tank 4 through a water intake 56 located below the heat exchanger 54 in the hot water storage tank 4. The water taken in from the water intake 56 exchanges heat with the hot water in the upper part of the hot water tank 4 while passing through the heat exchanger 54, and is almost the same as the water stored in the upper part of the hot water tank 4 when leaving the hot water tank 4. It becomes the same temperature. The water exiting the hot water tank 4 is supplied to the mixing unit 6.

When the hot water in the hot water tank 4 is used and the hot water is pushed up above the water intake 56, the temperature of the water taken into the water intake 56 begins to drop rapidly. However, warm water remains above the water intake 56, and heat is exchanged with water passing through the heat exchanger 54 to supply heat. The temperature of the water at the outlet of the heat exchanger 54 is approximately equal to the temperature of the hot water remaining in the hot water tank 4.
The temperature of the hot water remaining in the hot water tank 4 is reduced by supplying heat to the water in the heat exchanger 54, so that the temperature of the hot water that passes through the heat exchanger 54 and enters the mixing unit 6 also starts to decrease. The timing at which the hot water temperature T1 entering the mixing unit 6 begins to drop is earlier than that of the conventional hot water supply apparatus in which the hot water supply pipe 14 connecting the hot water storage tank 4 and the mixing unit 6 communicates with the uppermost part of the hot water storage tank 4. . Moreover, since the hot water remaining in the hot water tank 4 heats the water taken in from the water intake 56, the temperature T1 changes gradually.
The control means 30 can start the control of the mixing unit 6 early in order to cope with the hot water out of the hot water tank 4 that can be known at an earlier timing. Further, since the change in the temperature T1 gradually proceeds, if the throttle control of the tap water valve of the mixing unit 6 and the control of the combustion amount of the heating device 8 are performed at a normal speed, the temperature change of the warm water should be well followed. Can do. Thereby, the hot water supply apparatus 52 can keep the temperature of the hot water supplied to the hot water use location 20 substantially constant even when the hot water storage tank 4 runs out of hot water.

(4th Example) The hot water supply apparatus 62 of a present Example is shown in FIG. A hot water supply pipe 14 connecting the hot water storage tank 4 and the mixing unit 6 communicates with the hot water storage tank 4 at two or more places in the hot water storage tank 4 having different heights. That is, a hot water supply pipe 14 connecting the hot water storage tank 4 and the mixing unit 6 extends into the hot water storage tank 4 and communicates with the hot water supply pipe 14, and intake ports 64 a, 64 b, 64 c, 64 d are provided at different heights. Is provided. From the intake ports 64a, 64b, 64c, 64d, an approximately equal amount of water enters the tapping pipe 14.

  The contents of the hot water supply operation of the hot water supply device 62 will be described with reference to FIG. The dotted lines in FIG. 8 indicate changes in the temperature of hot water supplied from the highest intake port 64a and changes in the temperature of hot water supplied from the lowest intake port 64d. As the hot water in the hot water tank 4 is used, the remaining hot water is pushed upward, so that the temperature of the water in the hot water tank 4 supplied from the lower intake port 64d starts to decrease most quickly. At this time, the hot water supplied from the higher intake ports 64a, 64b, 64c is stable at a high temperature. Hot water taken from different positions of the hot water tank 4 is mixed in the hot water supply pipe 14 and enters the mixing unit 6. The warm water temperature T1 of the mixing unit 6 is substantially equal to a weighted average value taking into account the amount of warm water taken from the water intakes 64a, 64b, 64c, 64d, and the water whose temperature has dropped from the water intake 64d is mixed. As it begins to arrive at 6, the temperature entering the mixing unit 6 decreases. Thereafter, in the process in which the hot water is further utilized and the remaining hot water is pushed up to the top, the temperature of the water entering the tap pipe 14 from the water intakes 64c, 64b, 64a is also rapidly lowered. However, since the water from all intake ports with different temperatures is mixed and supplied to the mixing unit 6, the temperature T1 gradually decreases until the temperature of the tap water is reached.

  When the temperature T1 starts to decrease, the control unit 30 performs an operation of gradually reducing the tap water valve of the mixing unit 6 and, when the temperature further decreases, ignites the heating device 8. The sign of hot water running out can be known at an early timing by the change of the temperature T1, and the temperature of the hot water is gradually decreased, so that the tap operation of the tap water valve of the mixing unit 6 and the heating device 8 are performed. Even when the ignition process is performed at a normal operation speed, it is possible to cope with a decrease in the temperature of the hot water from the hot water tank 4. The hot water supply temperature of the hot water supply device 62 can be kept approximately within the hot water supply set temperature even when the hot water tank 4 runs out of hot water.

(5th Example) The cogeneration system of a present Example is shown in FIG. In the cogeneration system of the present embodiment, a difference is provided between the communication height of the hot water supply pipe 14 with the hot water storage tank 4 and the communication height of the power generation heat recovery pipe 12 with the hot water storage tank 4. The power generation heat recovery pipe 12 communicates with the hot water storage tank 4 at a height below the communication height of the hot water supply pipe 14 by a predetermined distance.

When the power generation is started, the circulation pump 22 provided in the power generation heat recovery pipe 12 is operated, and the cold water taken out from the lower water intake 74 of the hot water tank 4 passes through the power generation heat recovery pipe 12. The cold water in the power generation heat recovery pipe 12 exchanges heat with the fuel cell 36 and the reformer 34 to become hot water. The hot water in the power generation heat recovery pipe 12 returns to the hot water tank 4 from the hot water return port 76 at a height below the uppermost part of the hot water tank 4 by a predetermined distance.
Immediately after the start of power generation, the hot water tank 4 is filled with cold water. The hot water that has entered the hot water tank 4 from the hot water return port 76 causes convection above the hot water return port 76 and mixes with the stored cold water. The temperature of the water in the hot water tank 4 above the hot water return port 76 becomes uniform. The water in the hot water storage tank 4 below the hot water return port 76 does not generate convection, so that the temperature does not change and the state of cold water is maintained.
When power generation is continued and hot water continues to be supplied from the power generation heat recovery pipe 12, the temperature of the water above the hot water return port 76 of the hot water tank 4 gradually rises while being made uniform by convection, and the power generation heat recovery pipe The temperature is almost the same as the temperature of the hot water supplied from. When the power generation is further continued, the hot water layer falls below the hot water return port 76 and the cold water layer accumulates at the bottom of the hot water tank 4.

  When hot water is supplied during power generation, hot water is taken in from the hot water supply pipe 14 communicating with the uppermost part of the hot water tank 4. When hot water more than the amount supplied from the power generation heat recovery pipe 12 is used and the amount of hot water in the hot water storage tank 4 is reduced, water is supplied from the water supply pipe 10 at the bottom and the hot water is pushed up to the upper part of the hot water storage tank 4. . When the hot water layer is pushed up above the hot water return port 76 and the cold water layer reaches around the hot water return port 76, convection occurs between the hot water supplied from the power generation heat recovery pipe 12 and the surrounding cold water. The warm water above the warm water return port 76 has a uniform temperature distribution. If the use of hot water exceeding the supplied amount continues, convection occurs above the hot water return port 76, and the temperature gradually decreases while maintaining a uniform temperature distribution. At this time, the temperature T1 is substantially the same as the temperature at the top of the hot water tank 4.

The distance from the top of the hot water storage tank 4 of the hot water return port 76 to the response time of the tap water valve of the mixing unit 6 and the required time until the heating device 8 can supply hot water at the set temperature after receiving the ignition command. By setting based on this, it is possible to adjust the amount of change in the temperature T1 when the hot water remaining in the hot water tank 4 is pushed up above the hot water return port 76.
For example, the response time of the tap water valve of the mixing unit 6 requires a response time of 1 minute from fully open to fully closed, and is 1 from the time when the heating device 8 receives the ignition command until the hot water at the set temperature can be supplied. If the maximum hot water supply capacity of the heating device 8 is equivalent to No. 24, the amount of hot water that can be stored above the hot water return port 76 of the hot water tank 4 is 24 liters or more, more preferably 30 liters. It is desirable to set it above. As the amount of hot water that can be stored above the hot water return port 76 of the hot water tank 4 increases, the hot water is pushed up above the hot water return port 76, and when the temperature T1 starts to drop, A large amount of hot water remains. When the hot water supply is supplied to the hot water usage point 20 to the maximum and the temperature T1 starts to drop, the control means 30 closes the valve of the mixing unit 6 step by step and ignites the heating device 8. Order. 24 liters of hot water corresponding to the amount of hot water remaining in the upper part of the hot water tank is taken out from the hot water supply pipe 14 during one minute from when the heating device 8 prepares for ignition and starts to supply hot water at the set temperature. Hot water is supplied. At this time, convection of the remaining hot water and cold water occurs in the upper part of the hot water tank 4, and the temperature gradually decreases while being made uniform, and the temperature T1 gradually decreases accordingly. By adjusting the tap water valve of the mixing unit 6 in stages, the hot water supply temperature is adjusted so as not to drop too much. By heating the hot water so that the heating device 8 ignites and reaches the set temperature after 1 minute, the hot water at the set temperature is supplied to the hot water use location 20.

  In this way, the hot water heater 72 of this embodiment has a moderate temperature of the hot water supplied from the hot water tank 4 even when hot water of an amount higher than the amount supplied from the power generation heat recovery pipe 12 is used during power generation. descend. The control means 30 responds to the temperature change of the hot water supplied from the hot water storage tank 4 and controls the mixing ratio of the tap water of the mixing unit 6 and the combustion amount of the heating device 8, thereby supplying hot water at the hot water usage point 20. The temperature can always be maintained near the set temperature.

(6th Example) The cogeneration system of a present Example is shown in FIG. The hot water storage tank 4 of the hot water supply apparatus 82 of the present embodiment is provided with a heat exchanger 84 at the top. The hot water return port 76 is provided below the heat exchanger 84, and the power generation heat recovery pipe 12 communicates with the water intake port 74 at the bottom of the hot water tank 4 and the hot water return port 76.

The cogeneration system has a low-temperature load path 86 that takes water from the cistern 90, passes through the heat exchanger 84 of the hot water tank 4, exchanges heat with the low-temperature load 92 such as floor heating, and returns to the cistern 90. Is provided. When the low temperature load 92 is operated, the pump 94 is operated and the water of the cistern 90 circulates through the low temperature load path 86. The water in the cis turn 90 is warmed when passing through the heat exchanger 84 in the hot water tank 4 to become hot water, and heat is exchanged with the low temperature load 92 to supply heat and return to the cis turn 90.
If the temperature of the water does not rise sufficiently even if the hot water storage tank 4 runs out of water and passes through the heat exchanger 84, the auxiliary heating device 88 is ignited to warm the water circulating in the low-temperature load path 86.

  When the low temperature load 92 is operated, it is desirable that sufficient heat is supplied to the water in the low temperature load path 86 by the heat exchanger 84 and the auxiliary heating device 88 is not used as much as possible. When power generation is being performed, the hot water above the hot water return port 76 of the hot water tank 4 is substantially the same temperature as the hot water supplied from the power generation heat recovery pipe 12 and is in a uniform temperature state. Sufficient heat can be supplied to the water passing through the vessel 84. Furthermore, while the hot water at the upper part of the hot water tank 4 is supplying heat by heat exchange, the temperature at the upper part of the hot water tank 4 is maintained at the same uniform temperature as the hot water supplied from the power generation heat recovery pipe 12 by convection. Therefore, sufficient heat can be supplied to the water passing through the heat exchanger 84 continuously.

  The hot water in the hot water storage tank 4 can supply heat to the low temperature load 92 and can supply hot water similar to that in the fifth embodiment. When the hot water tank 4 runs out of hot water, the temperature of the hot water supplied from the hot water tank 4 gradually decreases, so that the control means 30 performs mixing in response to the temperature change of the hot water supplied from the hot water tank 4. By controlling the mixing ratio of the tap water of the unit 6 and the combustion amount of the heating device 8, the hot water supply temperature of the hot water use location 20 can always be maintained near the set temperature.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. For example, the mixing ratio of hot water and tap water in the mixing unit is determined based on the measurement result of the temperature of hot water and tap water entering the mixing unit, but the mixing unit's hot water and tap water is based on the outlet temperature of the mixing unit. A mixing ratio may be determined. When the pipe connecting the hot water storage tank and the mixing unit communicates with the hot water storage tank at a position where the height of the hot water storage tank is different, there is no particular limitation as long as there are two or more communication points. The means for communicating the generated heat recovery pipe downward from the uppermost part of the hot water tank by a predetermined distance may extend the generated heat recovery pipe downward by a predetermined distance inside the hot water tank. In addition, the piping and the configuration of the supply path shown in the drawings of the embodiments can be freely changed depending on the configuration of the apparatus.

The figure which shows the structure of the cogeneration system of Example 1 typically. The figure which shows typically the change of the hot water temperature of the cogeneration system of Example 1, and the supply amount of fuel gas. The figure which shows the structure of the cogeneration system of Example 2 typically. The figure which shows typically the change of the hot water temperature of the cogeneration system of Example 2, and the supply amount of fuel gas. The figure which shows the structure of the cogeneration system of Example 3 typically. The figure which shows the change of the hot water temperature of the cogeneration system of Example 3, and the supply amount of fuel gas. The figure which shows the structure of the cogeneration system of Example 4 typically. The figure which shows the change of the hot water temperature of the cogeneration system of Example 4, and the supply amount of fuel gas. The figure which shows the structure of the cogeneration system of Example 5 typically. The figure which shows the structure of the cogeneration system of Example 6 typically. The figure which shows the structure of the conventional cogeneration system typically. The figure which shows typically the change of the hot water temperature of the conventional cogeneration system, and the supply amount of fuel gas.

Explanation of symbols

2, 42, 52, 62, 72, 82, 100: Hot water supply device 4, 104: Hot water storage tank 6, 106: Mixing unit 8, 108: Burner 10, 110: Water supply path 12, 112: Power generation heat recovery paths 14, 16 , 18, 40, 44, 114, 116, 118: piping 20, 120: hot water use locations 22, 94, 122: circulation pumps 24, 26, 124, 126: temperature sensors 32, 102: generators 34, 130: modified 36, 132: Fuel cell 54: Heat exchanger 56, 64a, 64b, 64c, 64d, 74: Water inlet 76: Hot water return port 86: Low temperature load path 90: Systurn 92: Low temperature load

Claims (1)

It has a hot water storage tank, a mixing unit that mixes hot water from the hot water tank and tap water, a heating device that heats the water after passing the mixing unit, and a hot water supply pipe that supplies hot water that has passed through the heating device to the hot water use location. A water heater,
A water supply pipe that supplies tap water is connected to the hot water pipe that connects the hot water storage tank and the mixing unit .
A hot water supply apparatus characterized in that hot water from a hot water storage tank is mixed with tap water from a water supply pipe and then mixed with tap water in a mixing unit .

Images